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I am trying to take random username and password from an array, and checking whether current username password is same as previous username password. If it is same, i want to take different user id, pass from the array. I wrote below code, but I it also picks up same username passwords.

let usernames = ["uname1", "uname2"],
        passwords = ["pass1", "pass1"];

    let rand, prevRand;
    prevRand = _.random(0, usernames.length - 1);
    rand = _.random(0, usernames.length - 1);

    console.log("rand " + rand)
    console.log("prevrand " + prevRand)


    if (rand !== prevRand) {
        console.log("uname!==: " + usernames[rand])
        console.log("pass!==: " + passwords[rand])
        prevRand = rand;
    } else {
        while (rand !== prevRand) {
            rand = _.random(0, usernames.length - 1);
            console.log("newrand " + rand)

        }
        prevRand = rand;
        console.log("unamenew " + usernames[rand])
        console.log("passnew " + passwords[rand])

    }

Please correct my logic here..Thanks.

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  • Please add the lodash or underscorejs tag to indicate which library you're using. Commented Feb 4, 2018 at 6:48
  • while (rand !== prevRand) { should be while (rand == prevRand) {. The way you wrote it forces rand to be the same as prevRand when the loop finishes. Commented Feb 4, 2018 at 6:49

2 Answers 2

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Your while (rand !== prevRand) loop is never executed because it is inside the else statement wich means that rand == prevRand. Try changing the while loop to do..while.

Check the example (I've replaced _.random with Math.random to run without external libraries)

let usernames = ["uname1", "uname2", "uname3", "uname4"],
    passwords = ["passw1", "passw2", "passw3", "passw4"];

let rand, prevRand;
prevRand = Math.floor(Math.random() * (usernames.length));
rand = Math.floor(Math.random() * (usernames.length));

console.log("rand " + rand)
console.log("prevrand " + prevRand)


if (rand !== prevRand) {
    console.log("uname " + usernames[rand])
    console.log("pass " + passwords[rand])
    prevRand = rand;
} else {
    do {
        rand = Math.floor(Math.random() * (usernames.length));
        console.log("newrand " + rand)
    } while (rand == prevRand);
    prevRand = rand;
    console.log("unamenew " + usernames[rand])
    console.log("passnew " + passwords[rand])
}

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2 Comments

So after making the changes you said, after the if/else loop, if I use the value of rand to get the username in another variable it will be correct?
@AforApple After the loop rand will hold other value than prevRand, so usernames[rand] will differ from usernames[prevRand]. As well as passwords
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rand === prevRand is true in the else case, so it will never enter the while cycle.

The cycle, instead, must loop while rand is equal to prevRand

  while (rand === prevRand) {
        rand = _.random(0, usernames.length - 1);
        console.log("newrand " + rand)
 }

Each time they are equal a new value to rand should be given, so they can be different.

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1 Comment

So after making the changes you said, after the if/else loop, if I use the value of rand to get the username in another variable it will be correct?

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